Recording tape cartridge

ABSTRACT

Sliding resistance at a time when a locking member is moved between a locking position and an unlocking position with respect to a reel can bc lessened, and deformation of a flange welded to a hub also can be suppressed. In a recording tape cartridge  10  in which a reel  20 , at which an upper flange  24  is welded to a hub  22 , is singly and rotatably accommodated within a case  12 , a locking member  70  is configured to be able to rotate within a plane orthogonal to a rotation axis direction of the reel  20  around a position which is different from a rotational center of the reel  20 . The locking member  70  is set at a locking position, at which the locking member  70  is interposed on an extended line of the hub  22  in the rotation axis direction at a side where the upper flange  24  is welded and the locking member  70  impedes movement of the reel  20  in the rotation axis direction, and an unlocking position, at which the locking member  70  is withdrawn from the extended line of the hub  22  in the rotation axis direction at the side where the upper flange  24  is welded and the locking member  70  permits movement of the reel  20  in the rotation axis direction.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC 119 from Japanese PatentApplication No. 2006-163708, the disclosure or which is incorporated byreference herein.

BACKGROUND OF THF. INVENTION

1. Field of the Invention

The present invention relates to a recording tape cartridge whichaccommodates, within a case, a single reel on which is wound a recordingtape, such as a magnetic tape or the like, which is used as arecording/playback medium mainly of computers or the like.

2. Description of the Related Art

Them have conventionally been known recording tape cartridges in which arecording tape, such as a magnetic tape or the like which is used as adata recording/playback medium (for data backup) of computers or thelike, is wound on a reel, and the reel is singly and rotatablyaccommodated within a case which is made of a synthetic resin. Such arecording tape cartridge is generally structured such that at the timewhen the recording tape cartridge is not in use (is not loaded in adrive device) the reel is mechanically braked in the rotating direction,and, in the rotation axis direction, is merely urged by an urging meanssuch as a compression coil spring or the like.

However, here, if an impact is applied to the recording tape cartridgedue to the recording tape cartridge being handled by a user or beingdropped or the like when the recording tape cartridge is not in use, dueto this impact, the reel easily moves in the rotation axis direction,and, depending on the case, there is the problem that the rotatingdirection braking of the reel is cancelled and wrinkles or the like areformed in the recording tape. Therefore, in recent years, recording tapecartridges have been proposed which are structured such that, when notin use, the reel is restricted so as to not move in the rotation axisdirection, and, when in use, this restriction is released simply, suchas disclosed in Japanese Patent Application Laid-Open (JP-A) No.2005-276416 for example.

The above-described recording tape cartridge is structured such that,when the recording tape cartridge is not in use, locking membersenter-in between an upper flange of the reel and a ceiling plate of thecase, and the reel is thereby restricted so as to not move in therotation axis direction. Namely, the leeway for the reel to move in therotation axis direction is eliminated by the locking members. When therecording tape cartridge is being used, a releasing operation, in whicha braking member which restricts the reel so as to not move in therotating direction is raised-up by a releasing member of the drivedevices is utilized such that a taper portion formed at the lockingmembers is pushed, and the locking members are thereby slid in a radialdirection of the reel and withdrawn (the restriction of the lockingmembers is released).

In order to ensure space for movement of the locking members in theradial direction of the reel due to the braking member moving in therotation axis direction of the reel, the angle of the taper portionformed at the locking member is made to be 45°. However, if the taperportion of the locking members is 45°, the component of force of theforce applied in the rotation axis direction of the reel works greatly,and therefore, rubbing arises between the locking members and the innersurface of the ceiling plate of the case, and there is the problem thatthe powder-like substance generated at the time of this rubbingincreases the sliding resistance (the dynamic friction coefficient) ofthe locking members with respect to the inner surface of the ceilingplate of the case.

When the sliding resistance (the dynamic friction coefficient) of thelocking members with respect to the inner surface of the ceiling plateof the case increases, a very large moving force (lock releasing force)in the rotation axis direction of the reel is needed at the brakingmember. Therefore, overload is applied to the driving source whichlowers the recording tape cartridge relative to a reference plane of thedrive device, and trouble or the like is brought about at the drivedevice. Further, there are cases in which tight-winding deformationarises at the hub of the reel due to the recording tape being wound ontothe hub. In such cases, there is the problem that the flanges which arewelded to the hub deform in directions of approaching the recordingtape.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above circumstances,and provides a recording tape cartridge.

A first aspect of the present invention provides a recording tapecartridge comprising: a reel having a hub on which a recording tape iswound, and flanges holding the recording tape wound on the hubs at leastone of the flanges being welded to the hub; a case accommodating thereel singly and rotatably; and a locking member configured to be able torotate within a plane which is orthogonal to a rotation axis directionof the reel around a position which is different from a rotationalcenter of the reel, the locking member being set at a locking position,at which the locking member is interposed on an extended line of the hubin the rotation axis direction at a side where the flange is welded andthe looking member impedes movement of the reel in the rotation axisdirection, and an unlocking positions at which the locking member iswithdrawn from the extended line of the hub in the rotation axisdirection at the side where the flange is welded and the locking memberpermits movement of the reel in the rotation axis direction.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will be described in detail basedon the following figures, wherein:

FIG. 1 is a schematic perspective view of a recording tape cartridge;

FIG. 2 is a schematic side cross-sectional view of the recording tapecartridge before the raising of a rotating shaft;

FIG. 3 is a schematic side cross-sectional view of the recording tapecartridge after the raising of the rotating shaft;

FIG. 4 is a schematic exploded perspective view showing the relationshipbetween locking members and a banking member;

FIG. 5 is a schematic perspective view of the braking member;

FIG. 6 is a schematic plan view of the braking member;

FIG. 7 is a schematic side view of the braking member;

FIG. 8 is a schematic plan view of the locking member;

FIG. 9 is a schematic side view of the locking member;

FIG. 10 is a schematic cross-sectional view showing the shape of a camgroove portion of the locking member;

FIG. 11 is a schematic exploded perspective view showing a mountingstructure of the locking member to an inner surface of a ceiling plateof an upper case;

FIG. 12A and FIG. 12B are schematic perspective views showing rotationoperation of the locking member; and

FIG. 13 is a schematic plan view showing the rotation operation of thelocking members.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an example of an exemplary embodiment of the presentinvention will be described in detail with reference to the drawings.Note that, for convenience of explanation, in FIG. 1, the direction ofloading a recording tape cartridge 10 into a drive device is indicatedby arrow A, and this is the forward direction (front side) of therecording tape cartridge 10. The direction of arrow b, which isorthogonal to arrow A, indicates the right direction (right side), thedirection of arrow C indicates the upward direction (upper side), andfront, back, left, right, up, down are expressed on the basis of thesedirections. Further, the expression “radial direction” hereinafter meansa direction parallel to a direction which is oriented radially outwardfrom the axially central (central) line of a reel accommodated in acase.

As shown in FIG. 1 through FIG. 3, the recording tape cartridge 10 has asubstantially rectangular box-shaped case 12. The case 12 is structuredby an upper case 14 and a lower case 16, which are molded of a syntheticresin material containing polycarbonate (PC) or acrylonitrile butadienestyrene (ABS) as the main component thereof, e.g., a synthetic resinmaterial in which glass fibers (GF) are mixed-together with PC, beingjoined together by ultrasonic welding or screws or the like, in a statein which a peripheral wall 14B, which stands erect at the peripheraledge of a ceiling plate 14A of the upper case 14, and a peripheral wall16B, which stands erect at the peripheral edge of a floor plate 16A ofthe lower case 16, abut one another.

A single reel 20 is rotatably accommodated within the case 12. The reel20 is structured such that a reel hub 22, which is shaped as acylindrical tube having a floor and which structures an axially centralportion of the reel 20, and a lower flange 26, which is provided at alower end portion of the reel hub 22, are molded integrally, and anupper flange 24 is ultrasonically welded to an upper end portion of thereel hub 22 in a state in which an annular extended portion 24A, whichstands erect at an inner peripheral edge portion of the upper flange 24,engages with (contacts) the inner peripheral surface of the reel hub 22.A recording tape T, such as a magnetic tape or the like which serves asan information recording/playback medium, is wound on the outerperipheral surface of the reel hub 22. The transverse direction endportions of the recording tape T wound thereon are held by the upperflange 24 and the lower flange 26. Note that the inner diameter of thereel hub 22 is less than or equal to 48 mm.

A reel gear 32 is formed in an annular shape at the bottom surface of afloor wall 28 of the reel hub 22. A gear opening 30, which is forexposing the reel gear 32 to the exterior, is formed in a centralportion of the lower case 16. Due to the reel gear 32, which is exposedfrom the gear opening 30, meshing-together with a driving gear 102formed at a rotating shaft 100 of the drive device and being rotated anddriven thereby, the reel 20 can rotate relative to the case 12 withinthe case 12. Further, an annular reel plate 34 formed of a magneticmaterial is fixed by insert molding or the like to the radial directioninner side of the reel gear 32, at the bottom surface of the floor wall28. The reel plate 34 is attracted to and held by the magnetic force ofan annular magnet (not shown) which is provided at the rotating shaft100 of the drive device.

An opening 18 for pulling-out of the recording tape T wound on the reel20, is formed at a front portion of a right wall 12B of the case 12. Aleader pin 40, which is pulled-out and manipulated while being anchored(engaged) by a pullout member (not shown) of the drive device, is fixedto a free end portion of the recording tape T which is pulled-out fromthe opening 18. Annular grooves 42 are formed at both end portions ofthe leader pin 40 which project-out further than the transversedirection end portions of the recording tape T. The annular grooves 42are anchored by hooks or the like of the pull-out member. In this way,at the time when the recording tape T is pulled-out, the hooks or thelike do not contact and scratch the recording tape T.

A pair of upper and lower pin holding portions 36, which position andhold the leader pin 40 within the case 12, are provided at an inner sideof the opening 18 of the case 12, i.e., at the inner surface of theceiling plate 14A of the upper case 14 and the inner surface of thefloor plate 16A of the lower case 16. The pin holding portions 36 areformed in substantially semicircular shapes whose recording tape Tpull-out sides are open. Both end portions 44 of the leader pin 40,which is in an upright state, can enter into and exit from the pinholding portions 36 from the open sides.

A plate spring (not shown) is disposed and fixed in a vicinity of thepin holding portions 36, Bifurcated distal end portions of the platespring respectively engage with the upper and lower end portions 44 ofthe leader pin 40, such that the leader pin 40 is held in the pinholding portions 36. Note that when the leader pin 40 is to enter intoor exit from the pin holding portions 36, the distal end portions of theplate spring are appropriately elastically deformed so as to permitmovement of the leader pin 40.

The opening 18 is opened and closed by a door 46. The door 46 is formedin the shape of a substantially rectangular plate of a size which canclose the opening 18, and is always urged in the direction of closingthe opening 18 by an urging member (not shown) such as a coil spring ora torsion spring or the like. Further, groove portions 38, into whichthe upper and lower end portions of the door 46 are slidably fit, areformed in the ceiling plate 14A and the floor plate 16A at the innerside of the opening 18, such that the door 46 can move along the rightwall 12B of the case 12. Moreover, a convex portion 46A foropening/closing operation projects outwardly from the front end portionof the door 46. The convex portion 46A engages with an opening/closingmember (not shown) of the drive device as the recording tape cartridge10 is loaded into the drive device. The door 46 is thereby openedagainst the urging force of the urging member.

Plural standing ribs 25 of predetermined heights project-out at uniformintervals at the inner peripheral surface of the reel hub 22. Pluralengaging gears 48 stand erect at uniform intervals so as to be separatedat predetermined intervals at the peripheral edge of the top surface ofthe floor wall 28 of the reel hub 22 (e.g., three engaging gears 48 atintervals of 120°). Between the engaging gears 48, plural through holes29 are formed at predetermined positions which are above the reel gear32 (in this case, three through holes 29 at intervals of 120°).

Further, as shown in FIGS. 2 through FIG. 4, a substantially cylindricalboss 64 projects to a predetermined height at the substantial center ofthe inner surface of the ceiling plate 14A of the upper case 14. Fromthe peripheral surface of the boss 64 to the inner surface of theceiling plate 14A, four rotation restricting ribs 66, which aresubstantially trapezoidal in side view, project integrally topredetermined heights at uniform intervals so as to be substantiallycross-shaped in bottom view. Engaging ribs 68, which are substantiallyflat-plate-shaped and which run substantially along the peripheraldirection of the reel 20, project-out at the inner surface of theceiling plate 14A at the radial direction distal end portions of therotation restricting ribs 66, and the rotation restricting ribs 66 areconnected integrally to the central portions thereof. Note that theheights of the engaging ribs 68 and the height of the boss 64 aresubstantially equal.

On the other hand, a braking member 50 serving as a moving member isinserted within the reel hub 22. The braking member 50 is molded of asynthetic resin material containing, for example, polyacetal (POM),polyamide (PA), or polybutylene terephthalate (PBT) as the maincomponent, substantially in the shape of a disc which is accommodatedwithin the reel hub 22 so as to be able to move up and down (so as to beable to move in the rotation axis direction of the reel 20).

Further, as shown in FIG. 2 through FIG. 7, a braking gear 54, which canmesh with the engaging gears 48, is formed in an annular form at theperipheral edge of a bottom surface 50A of the braking member 50. Anengaging wall portion 56, which serves as a guide portion and isprovided with a groove portion 56A which is substantially cross shapedin plan view and into whose interior the boss 64, the rotationrestricting ribs 66, and the engaging ribs 68 are inserted, stands erectat the center of the top surface of the braking member 50 so as to beslightly taller than the heights of the boss 64 and the engaging ribs68.

Pairs of partitioning portions 56B, which prescribe spaces foraccommodating the engaging ribs 68, project within the groove portion56A to substantially the same height as the engaging wall portion 56.The interval between the partitioning portions 56B is formed to beslightly larger than the plate thickness of the rotation restricting rib66. In this way, the braking member 50 cannot rotate with respect to thecase 12 (the upper case 14), and can move within the reel hub 22 upwardand downward (the rotation axis direction of the reel 20) while beingguided so as to not tilt.

A compression coil spring 80 serving as an urging member is disposedbetween the upper case 14 and the braking member 50. Namely, one end(the upper end) of the compression coil spring 80 abuts a region betweenthe engaging ribs 68 (the engaging wall portion 56) and spring stoppers84 (to be described later) which project-out at the inner surface of theceiling plate 14A further toward the outer side than the engaging ribs68 (the engaging wall portion 56). The other end (lower end) of thecompression coil spring 80 is disposed in a state of abutting a regionbetween the engaging wall portion 56 and an annular projection 58, whichis provided at the top surface of the braking member 50 further towardthe outer side than the engaging wall portion 56.

The braking member 50 is always urged downward by the urging force ofthe compression coil spring 80. Accordingly, when the recording tapecartridge 10 is not in use (is not loaded in the drive device), therecording tape cartridge 10 is in a state in which the braking gear 54is always meshed-together with the engaging gear 48, and is in arotation locked state in which relative rotation of the reel 20 withrespect to the case 12 is impeded. Note that, at this time, the reel 20is pressed against the lower case 16 side by this urging force, and thereel gear 32 is exposed from the gear opening 30.

A releasing member 60, which is molded of a resin material and issubstantially triangular in plan view, is inserted within the reel hub22 at the lower side of the braking member 50 (between the floor wall 28and the braking member 50). Leg portions 62, which are inserted throughthe through holes 29 and project-out from the bottom surface of thefloor wall 28 to predetermined heights above the reel gear 32, projectat the bottom surface of the releasing member 60 at the respectivevertices thereof. A substantially hemispherical releasing projection 52,which projects at the center of the bottom surface 50A of the brakingmember 50, abuts the center of a top surface 60A which is a flat surfaceof the releasing member 60. In this way, the surface area of contactbetween the big member 50 and the releasing member 60 is reduced, andthe sliding resistance at the time of use (when the reel 20 rotates) islessened. Note that the releasing member 60 is molded of, for examplespolybutylene terephthalate (PBT).

As shown in detail in FIG. 6, plural (three in the illustratedstructure) engaging projections 55, which serve as operation portionsand are shaped as substantially arc-shaped plates in plan view, areprovided at uniform intervals and project to predetermined heights atthe top surface of the braking member 50 at the outer side of theannular projection 58. Accompanying the lock releasing operation (therising-up) of the braking member 50, the engaging projections 55 canrespectively enter into and abut the interiors of cam groove portions 76of plural (three in the illustrated structure) locking members 70 whichwill be described later, and, in the peripheral direction of the reel20, are curved toward the same direction.

As shown in FIG. 4 and in FIG. 8 through FIG. 13, the recording tapecartridge 10 has the locking members 70 which, when the recording tapecartridge 10 is not in use, restrict such that the reel 20 does not moveinadvertently in the rotation axis direction (upward and downward). Thelocking members 70 are configured to be able to rotate within ahorizontal plane orthogonal to the rotation axis direction of the reel20 around positions which are different from the rotational center ofthe reel 20, and can be set at locking positions (engaging positions) atwhich the locking members 70 are interposed on an extended line of thereel hub 22 in the rotation axis direction at the side where the upperflange 24 is welded and impede movement of the reel 20 in the rotationaxis direction, and unlocking positions (withdrawn positions) at whichthe locking members 70 are withdrawn from the extended line of the reelhub 22 in the rotation axis direction at the side where the upper flange24 is welded and permit movement of the reel 20 in the rotation axisdirection.

Namely, plural (three in the illustrated structure) mounting pins 82serving as supporting members project at uniform intervals at the innersurface of the ceiling plate 14A of the upper case 14 on a circumferencewhich is concentric with the axially central portion of the reel hub 22.The mounting pins 82 are inserted and fit in coil portions 92 of torsionsprings 90, which serve as urging members which urge the locking members70 in the directions of the locking positions, and through holes 78,which are formed in respective one end portions of the locking members70, in that order (see FIG. 11). After the mounting pins 82 are insertedand fit therein, the locking members 70 are mounted so as to be able torotate and so as to be prevented from falling-off from the mounting pins82, either by caulking (crushing) the distal ends of the mounting pins82 or by fitting-in an E ring (not shown) or the like.

Further, the spring stoppers 84 project at predetermined positions ofthe inner surface of the ceiling plate 14A. Respective one end portions94 of the torsion springs 90 are anchored on the spring stoppers 84.Other end portions 96 of the torsion springs 90 are anchored on thelocking members 70, and always urge the locking members 70 in thedirections of the locking positions. Accordingly, due to the urgingforces of the torsion springs 90, the locking members 70 rotateoutwardly in the radial direction of the reel 20 around the mountingpins 82, such that engaging portions 72 and engaging surfaces 74, whichwill be described later, can engage with the inner peripheral edgeportion, which includes the annular extended portion 24A of the upperflange 24, on the extended line of the reel hub 22 in the rotation axisdirection.

Note that slide stoppers 86, which impede rotation of the lockingmembers 70 beyond predetermined positions due to the urging forces ofthe torsion springs 90, project at the inner surface of the ceilingplate 14A in shapes which run substantially along the configurations ofthe side surfaces of the locking members 70 which the slide stoppers 86abut (i.e., substantially arc-shaped in plan view), at positions and toheights such that the slide stoppers 86 do not interfere with the topsurface of the upper flange 24 of the reel 20.

Further, the engaging portions 72 are formed at the other end portions(distal end portions) of the locking members 70 at the radial directionouter sides thereof. The engaging portions 72 engage, from the innerperipheral surface side of the reel hub 22, with the inner peripheraledge portion (including the annular extended portion 24A; the same holdshereinafter) of the upper flange 24 on the extended line of the reel hub22 in the rotation axis direction, and are interposed between the innersurface of the ceiling plate 14A and the top surface of the upper flange24, and impede movement of the reel 20 in the rotation axis direction(upward and downward).

The engaging portion 72 is formed in a substantial arc shape whichsubstantially runs along the configuration of the reel hub 22 in planview. When locked (engaged), a maximum width H (see FIG. 8) of theengaging portion 72 is larger than the plate thickness of the annularextended portion 24A of the upper flange 24 which engages with the innerperipheral surface of the reel hub 22 in plan view, and is of a sizesuch that the engaging portion 72 does not go beyond the outerperipheral surface of the reel hub 22, and preferably is of a size suchthat the engaging portion 72 substantially reaches the outer peripheralsurface of the reel hub 22. Further, the engaging portion 72 is formedto a size such that, when unlocked (withdrawn), the engaging portion 72can surely be accommodated within the reel hub 22 (see FIG. 13).Moreover, a thickness D (see FIG. 9) of the engaging portion 72 isformed to be substantially the same as a distance W (see FIG. 2) betweenthe inner surface of the ceiling plate 14A and the top surface of theupper flange 24 at the time when the reel 20 is positioned at itslowermost position within the case 12.

The engaging surface 74, which abuts the inner peripheral surface of thereel hub 22, is connected downwardly at the radial direction inner sideof the engaging portion 72. The engaging surface 74 is formed to be anarc-shaped surface of the same curvature which matches the innerperipheral surface of the reel hub 22 in plan view (see FIG. 13). Ataper surface 74A is formed at the lower end portion of the engagingsurface 74. Accordingly, the locking members 70, which are in the stateof being urged by the torsion springs 90 and abutting the slide stoppers86>are structured such that, when the recording tape cartridge 10 isbeing assembled (when the upper case 14 is placed on the lower case 16),accompanying this operation, the engaging portions 72 and the engagingsurfaces 74 can easily engage with the inner peripheral edge portion ofthe upper flange 24 on the extended line of the reel hub 22 in therotation axis direction.

Further, the cam groove portion 76, which has an inclined surface(sliding surface) 76A which is inclined downwardly in a substantial areshape in plan view toward the locking position direction side (the slidestopper 86 side), is formed at a predetermined position of the lockingmember 70 which position is further toward the through hole 78 side thanthe longitudinal direction central portion thereof. The engagingprojection 55 of the braking member 50 can enter into and abut the camgroove portion 76. As shown in FIG. 13, in the peripheral direction ofthe reel 20, the inclined surfaces 76A are formed so as to be curvedtoward the same direction, and extend in directions intersecting theloci of rotation, of the locking members 70 (in directions which do notrun along the loci of rotation of the locking members 70).

Accordingly, when the engaging projections 55 enter into the cam grooveportions 76 as the braking member 50 rises-up, distal end surfaces 55Aof the engaging projections 55 push the peak portions of the inclinedsurfaces 76A of the cam groove portions 76, and the distal end surfaces55A slide as are on the inclined surfaces 76A. In this way, the lockingmembers 70 can rotate toward the radial direction inner side (therotational center side) of the reel 20 around the mounting pins 82against the urging forces of the torsion springs 90, and the engagingportions 72 and the engaging surfaces 74 can withdraw from the innerperipheral edge portion of the upper flange 24 on the extended line ofthe reel hub 22 in the rotation axis direction.

In this way, the engaging portions 72 and the engaging surfaces 74 ofthe locking members 70 are configured to rotate (move) around themounting pins 82 between the locking positions (engaging positions) atwhich the engaging portions 72 and the engaging surfaces 74 arerestricted at the slide stoppers 86 and the unlocking positions(withdrawn positions) at which the engaging portions 72 and the engagingsurfaces 74 are withdrawn from the inner peripheral edge portion of theupper flange 24 on the extended line of the reel hub 22 in the rotationaxis direction, i.e., between positions on the extended line of the reelhub 22 in the rotation axis direction and the compression coil spring80, and the range of rotation (range of movement) thereof can be mademore compact.

Here, at an arbitrary position of the inclined surface 76A, an angle ofinclination θ, formed between the inclined surface 76A and an imaginaryplane orthogonal to the rotation axis direction of the reel hub 22, ismade to be greater or equal to 45°, as shown in the cross-sectional viewin FIG. 10. Even if the angle of inclination θ of the inclined surface76A is formed at such a steep slope, the moving distance of the lockingmember 70 can sufficiently be ensured. Namely, when the locking members70 are structured as described above even if the lock releasing force(pushing force) and the releasing (rising-up) stroke by the brakingmember 50 are small, the locking members 70 can be moved relativelygreatly. Therefore, the locking members 70 can be reliably rotated tothe unlocking positions (withdrawn positions).

Further, in order to make the slidability with respect to the ceilingplate 14A of the upper case 14 and the engaging projections 55 of thebraking member 50 good, the locking members 70 are molded of a syntheticresin material containing polyacetal (POM), polyamide (PA), orpolybutylene terephthalate (PBT) as the main component thereof, e.g., asynthetic resin material in which polytetrafluoroethylene (PTFE) orpolyethylene (PE) is mixed together with POM, or a synthetic resinmaterial in which molybdenum (Mo) is mixed together with PA, or thelike. In this way, a dynamic friction coefficient μ of the inclinedsurface 76A of the cam groove portion 76 and the distal end surface 55Aof the engaging projection 55 is less than or equal to 0.1.

Operation of the recording tape cartridge 10 which is structured asdescribed above will be described next. When the recording tapecartridge 10 is not in use (is not loaded in the drive device), theopening 18 is closed by the door 46. The reel 20 is urged downward bythe compression coil spring 80, via the braking member 50 and thereleasing member 60. Namely, due to the urging force of the compressioncoil spring 80, the braking gear 54 of the braking member 50 stronglymeshes together with the engaging gear 48 within the reel hub 22, andthe boss 64, the rotation restricting ribs 66, and the engaging ribs 68are inserted within the groove portion 56A of the engaging wall portion56. Inadvertent rotation of the reel 20 is thereby impeded.

Further, due to the urging forces of the torsion springs 90, the lockingmembers 70 are urged so as to rotate in the directions of the lockingpositions (engaging positions), and the engaging portions 72 and theengaging surfaces 74 are engaged with the inner peripheral edge portionof the upper flange 24 on the extended line of the reel hub 22 in therotation axis direction. Namely, the engaging surfaces 74 abut the innerperipheral surface of the annular extended portion 24A (the reel hub 22)at a predetermined pressures and the engaging portions 72 are interposedbetween the top surface of the upper flange 24 and the inner surface ofthe ceiling plate 14A. Note that at this time, the locking members 70are in states of being slightly separated from the slide stoppers 86,and are reliably engaged due to the urging forces of the torsion springs90.

Here, the thickness D of the engaging portion 72 of the locking member70 is formed to be substantially the same as the distance W between theinner surface of the ceiling plate 14A and the top surface of the upperflange 24 when the reel 20 is positioned at the lowermost positionwithin the case 12. Further, the three locking members 70 are providedat uniform intervals (at 120′ intervals). Accordingly, inadvertentrising-up of the reel 20 is stably impeded by the locking members 70.Namely, even if an impact is applied to the recording tape cartridge 10due to the recording tape cartridge 10 being dropped or the like,rotation of the reel 20 is impeded by the braking member 50, andfurther, movement of the reel 20 in the rotation axis direction (upwardand downward) is reliably impeded by the locking members 70.

By either caulking (crushing) the distal ends of the mounting pins 82 orfitting-in an E ring (not shown) or the like, the locking members 70 aremounted rotatably such that they are prevented from falling-off from themounting pins 82. Therefore, the molds for molding the upper case 14 andthe locking members 70 do not become complex, and the workability isgood. Further, because it suffices to provide the torsion springs 90 aswell at the mounting pins 82, assembly of the locking members 70 to theupper case 14 can be made easy.

Further, at the locking members 70, in plan view, the engaging surfaces74 are formed to be arc-shaped surfaces which have the same curvature asthe inner peripheral surface of the reel hub 22, and the engagingportions 72 are widths of extents such that the engaging portions 72 donot project-out from the outer peripheral surface of the reel hub 22 onthe extended line of the reel hub 22 in the rotation axis direction, andthe engaging portions 72 are interposed in substantial arc shapes whichsubstantially run along the configuration of the reel hub 22. Therefore,the surface area of the locking members 70 pressing the reel 20 (thesurface area of engagement) can be ensured to be a maximum. Namely, thelocking members 70 can suitably press the inner peripheral edge portionof the upper flange 24 on the extended line of the reel hub 22 in therotation axis direction.

In this way, the locking members 70 can suitably press the innerperipheral edge portion of the upper flange 24 which is welded to thereel hub 22. Therefore, force is suitably applied to the upper flange 24in the direction of separating from the transverse direction end portionof the recording tap T. Accordingly, deformation of the upper flange 24(deformation in the direction of approaching the transverse directionend portion of the recording tape T) due to tight-winding deformation ofthe reel hub 22 can be reliably suppressed.

When data is to be recorded onto the recording tape T of the recordingtape cartridge 10 or data which is recorded on the recording tape T ofthe recording tape cartridge 10 is to be played-back, the recording tapecartridge 10 is loaded into the drive device (not shown). Namely, therecording tape cartridge 10 is inserted into a loading opening (notshown) of the drive device along the direction of arrow A from the frontwall 12A side.

Then, first, an opening/closing member (not shown) which is provided atthe drive device engages with the convex portion 46A of the door 46. Inthis state, when the recording tape cartridge 10 moves further in thedirection of arrow A, the opening/closing member moves the convexportion 46A relatively backward against the urging force of the urgingmember. Thus, the door 46 from which the convex portion 46A projects isslid to the back side within the groove portions 38 along the right wall12B, and opens the opening 18.

When the recording tape cartridge 10 is loaded (inserted) into the drivedevice and the opening 18 is completely opened, the recording tapecartridge 10 is lowered a predetermined height, and positioning members(not shown) of the drive device are inserted into hole portions forpositioning (not shown) which are formed in the lower case 16. In thisway, the recording tape cartridge 10 is positioned accurately at apredetermined position within the drive device, and further sliding ofthe door 46 (further movement of the door 46 backward) is restricted.

Due to the operation of the recording tape cartridge 10 being lowered,the rotating shaft 100 rises up relatively and enters-in from the gearopening 30, and causes the driving gear 102 to mesh with the reel gear32. Thus, accompanying this operation of the driving gear 102 meshingwith the reel gear 32, the leg portions 62, which project-out above thereel gear 32, are pressed upward against the urging force of thecompression coil spring 80, and the braking member 50 is pressed upwardvia the releasing member 60, and the meshing-together of the brakinggear 54 and the engaging gear 48 is released. Note that, at this time,because the boss 64, the rotation restricting ribs 66, and the engagingribs 68 are inserted in the interior of the groove portion 56A of theengaging wall portion 56, the braking member 50 is in a state of beingguided and can move upward without tilting.

Then, in the state in which the driving gear 102 and the reel gear 32are completely meshed-together due to the reel plate 34 being attractedto and held by the magnetic force of an annular magnet (not shown) whichis provided further toward the inner side than the driving gear 102, thereel 20 is set in a lock released state in which the reel 20 can rotaterelative to the case 12 within the case 12 while the meshing-together ofthe reel gear 32 with the driving gear 102 is maintained.

Further, when the releasing member 60 moves upward, the braking member50 rises-up against the urging force of the compression coil spring 80,and the distal end surfaces 55A of the engaging projections 55 push thepeak portions of the inclined surfaces 76A at the cam groove portions 76of the locking members 70, and slide as are on the inclined surfaces76A. Thus, the locking members 70 rotate in the directions of theunlocking positions (withdrawn positions) around the mounting pins 82,against the urging forces of the torsion springs 90. At this time, theinclined surfaces 76A at the cam groove portions 76 and the engagingprojections 55 which abut these inclined surfaces 76A are formed insubstantial arc shapes in plan view which are both oriented in the samedirection in the peripheral direction of the reel 20. Therefore, theabutting/sliding state thereof can be maintained for a longer period oftime than if the inclined surfaces 76A and the engaging projections 55are formed to be rectilinear.

Further, the annular extended portion 24A stands erect at the upperflange 24 which the locking members 70 press. Therefore, when thelocking members 70 rotates to the unlocking positions, the time overwhich the locking members 70 press the inner peripheral edge portion ofthe upper flange 24 can be made to be longer by an amount correspondingto the region (the thickness) of the annular extended portion 24A.Accordingly, in a case in which, for example, the recording tapecartridge 10 is loaded in a drive device which is disposed vertically(in which the axis of the reel 20 is in the horizontal direction),offset of the reel 20 vertically downward can be suppressed by thelocking members 70, and poor chucking by the rotating shaft 100 of thedrive device (poor meshing-together of the driving gear 102 and the reelgear 32) can be avoided.

Further, the inclined surface 76A extends in a direction intersectingthe locus of rotation of the locking member 70, and, at an arbitraryposition thereof; the angle of inclination θ formed between the inclinedsurface 76A and an imaginary plane orthogonal to the rotation axisdirection of the reel hub 22 is made to be greater than or equal to 45°.Accordingly, due to the rising-up stroke of the braking member 50, theengaging surfaces 74 of the locking members 70 can be surely separatedfrom the inner peripheral surface of the annular extended portion 24A(the reel hub 22), and the engaging portions 72 of the locking members70 can be reliably withdrawn from between the top surface of the upperflange 24 and the inner surface of the ceiling plate 14A, and areaccommodated within the reel hub 22. In this way, the locking members 70are maintained in unlocked states, and the reel 20 is able to rise-up apredetermined height within the case 12, and is able to be rotated anddriven at the position of this predetermined height.

When the locking members 70 are configured to be set at the unlockingpositions (withdrawn positions) by rotating toward the rotational centerof the reel 20 in this way, dead space can be utilized effectively, andthe occurrence of problems such as the locking members 70 impeding therising-up of the reel 20 can be reliably prevented. Further, because thebraking member 50 rises-up without tilting as described above, theproblem of the lock releasing force (pushing force) with respect to thelocking members 70 increasing does not arise.

Moreover because the braking member 50 and the locking members 70 aremolded of POM, PA, PBT or the like and the upper case 14 as well ismolded of PC or the like, the slidability between the braking member 50(the engaging projections 55) and the locking members 70 (the cam grooveportions 76), and between the locking members 70 and the ceiling plate14A, improves. Further, because the locking members 70 are configured torotate (move) within a horizontal plane orthogonal to the rotation axisdirection of the reel 20, i.e., between the reel hub 22 and thecompression coil spring 80, the moving distances thereof are shortenedas compared with conventional locking members which move in the radialdirection of the reel 20.

Accordingly, the sliding resistance can be lessened, and, even in anenvironment in which acceleration impact is applied continuously, suchas the operation of loading into the drive device or the operation ofloading into a library device or the like, the slidability is notadversely affected. Accordingly, problems such as the lock releasingforce (pushing force) by the braking member 50 increasing do not arise,and it is possible to avoid bringing about breakage of the lockingmembers 70 or trouble with the drive device, or the like. Namely, duethereto, the recording tape cartridge 10 which can withstand use ofseveral ten-thousand times is obtained.

Moreover, the locking members 70 are not configured to move whilestraddling the compression coil spring 80, as is the case withconventional locking members. Accordingly, there is no need to providelimitations on the height of the compression coil spring 80, and thecoil diameter thereof can be made to be small. Further, because itsuffices for the space for the movement (rotation) of the lockingmembers 70 to be small as described above, the space for disposition ofthe compression coil spring 80 can be sufficiently ensured. Accordingly,the structures at the periphery of the locking members 70 can besimplified.

On the other hand, the pull-out member (not shown) provided at the drivedevice enters into the case 12 from the opening 18 which has beenopened, and grasps and pulls-out the leader pin 40 which is positionedand held at the pin holding portions 36. Note that, at this time,because the recording tape cartridge 10 is positioned accurately withinthe drive device, the pull-out member can reliably anchor the hooksthereof on the annular grooves 42 of the leader pin 40. Further, becausethe rotation locked state of the reel 20 is released, the reel 20 canrotate accompanying the operation of the pulling-out of the leader pin40.

In this way, the leader pin 40 which is pulled-out from the opening 18is accommodated at an unillustrated take-up reel. Then, due to thistake-up reel and the reel 20 being rotated and driven synchronously, therecording tape T is successively pulled-out from the case 12 while beingtaken-up onto the take-up reel, and recording or playback of informationis carried out by a recording/playback head (not shown) which isdisposed along a predetermined tape path.

When the recording tape cartridge 10 for which recording or playback ofinformation has been completed is to be ejected from the drive device,first, due to the rotating shaft 100 rotating reversely, the recordingtape T is rewound onto the reel 20. Then, when the recording tape T isrewound to the end on the reel 20 and the leader pin 40 is held at thepin holding portions 36, the recording tape cartridge 10 is raised up apredetermined height, and the positioning members (not shown) arepulled-out from the hole portions for positioning (not shown).

Then, when the rotating shaft 100 is lowered relatively and begins to bepulled-out from the gear opening 30, due to the urging force of thetorsion springs 90, the locking members 70 start to rotate around themounting pins 82 in the directions of the locking positions (theengaging positions). Namely, the distal end surfaces 55A of the engagingprojections 55 start to slide toward the peak portions of the inclinedsurfaces 76A at the cam groove portions 76. Then, when the rotatingshaft 100 is relatively lowered even further, the magnet (not shown)separates from the reel plate 34, the meshing-together of the drivinggear 102 with the reel gear 32 starts to be cancelled, and, at the pointin time when the meshed-together amount of the reel gear 32 and thedriving gear 102 decreases to about substantially half of the toothheight, the engaging portions 72 of the locking members 70 start to beinterposed between the top surface of the upper flange 24 and the innersurface of the ceiling plate 14A.

Namely, before the meshing of the driving gear 102 with the reel gear 32is completely cancelled (while the reel 20 is supported at the rotatingshaft 100), the locking members 70 are interposed between the topsurface of the upper flange 24 and the inner surface of the ceilingplate 14A and hold the reel 20 between the locking members 70 and thelower case 11, and impede rising-up of the reel 20. Accordingly, even incases in which the recording tape cartridge 10 is ejected from a drivedevice which is disposed vertically (in which the axis of the reel 20 isin the horizontal direction), the top surface of the reel 20 is pressedby the locking members 70 so as to be unable to rise-up. Therefore,locking by the locking members 70 is reliably carried out without thereel 20 becoming offset vertically downward, and positional offset(center offset) with respect to the case 12 is prevented.

Thereafter, when the rotating shaft 100 is relatively lowered furtherand the meshing of the driving gear 102 with the reel gear 32 iscompletely cancelled, the engaging portions 72 and the engaging surfaces74 engage with the inner peripheral edge portion of the upper flange 24on the extended line of the reel hub 22 in the rotation axis direction.Namely, due to the locking members 70 attempting to rotate to thelocking positions (engaging positions) at which the locking members 70abut the slide stoppers 86 due to the urging forces of the torsionsprings 90, the engaging surfaces 74 abut the inner peripheral surfaceof the annular extended portion 24A (the reel hub 22) at a predeterminedpressure, and the engaging portions 72 are completely interposed betweenthe top surface of the upper flange 24 and the inner surface of theceiling plate 14A.

Then, when the distal end surfaces 55A of the engaging projections 55separate from the inclined surfaces 76A of the cam groove portions 76,the braking member 50 and the releasing member 60 are pushed downward bythe urging force of the compression coil spring 80, and when the brakingmember 50 and the releasing member 60 are lowered to the lowermostposition within the case 12, the leg portions 62 are inserted throughthe through holes 29 and project-out to predetermined heights from thebottom surface of the floor wall 28 above the reel gear 32, and thebraking gear 54 meshes strongly with the engaging gear 48. In this way,the reel 20 is again set in a rotation locked state in which relativerotation thereof within the case 12 is impeded, and is set in a state inwhich inadvertent movement thereof in the rotation axis direction isimpeded

Thereafter, the recording tape cartridge 10 is moved in the directionopposite the direction of arrow A by an unillustrated ejectingmechanism. Thus, accompanying this movement, the door 46 is slid in thedirection of closing the opening 18 by the urging force of the urgingmember, and the opening 18 is completely closed (is returned to itsinitial state). In this way, the recording tape cartridge 10, at whichrelative rotation of the reel 20 with respect to the case 12 andmovement of the reel 20 in the rotation axis direction are locked and atwhich the opening 18 is closed, is completely ejected from the interiorof the drive device.

As described above, at the recording tape cartridge 10, the lockingmembers 70 which impede movement of the reel 20 upward and downward (inthe rotation axis direction) are configured to be able to rotate with ahorizontal plane orthogonal to the rotation axis direction of the reel20, around positions which are different from the rotational center ofthe reel 20. Therefore, as compared with locking members which move inthe radial direction of the reel 20, the moving distance thereof can beshortened, and, as a result, the sliding resistance can be lessened.Further, because the locking members 70 are structured to press theinner peripheral edge portion of the upper flange 24 which is welded tothe reel hub 22, force is applied to the upper flange 24 in thedirection of separating from the transverse direction end portion of therecording tape T. Accordingly, deformation of the upper flange 24(deformation in the direction of approaching the transverse directionend portion of the recording tape T) due to tight-winding deformation ofthe reel hub 22 can be suppressed.

Note that three of the locking members 70 are provided at uniformintervals in the above-described embodiment. However, it is preferableto provide at least three or more of the locking members 70 at uniformintervals. When three or more of the locking members 70 are provided atuniform intervals, movement of the reel 20 in the rotation axisdirection (upward and downward) can be impeded stably. Further, in theabove-described embodiment, the braking member 50 is configured to movein the rotation axis direction of the reel 20 (upward and downward)while being guided by the guide portion which extends in four directionsorthogonal to the moving direction of the braking member 50, i.e., whilebeing guided by the engaging wall portion 56 which is substantiallycross-shaped in plan view. However, it suffices for the guide portionwhich guides the braking member 50 to extend in at least threedirections orthogonal to the moving direction of the braking member 50.

Moreover, the inclined surfaces 76A of the cam groove portions 76 areformed in substantial arc shapes in plan view in the above-describedembodiment. However, the inclined surfaces 76A may be rectilinear inplan view, provided that the inclined surfaces 76A are structured suchthat the releasing stroke of the locking members 70 by the brakingmember 50 can be ensured. Further, when the locking members 70 arestructured in this way so as to be set at the locking positions and theunlocking positions by being rotated, the degrees of freedom in designof the diameter of the reel hub 22 increase. Namely, the locking members70 can be applied to various types of reel 20 at which the diameters ofthe reel hubs 22 are different.

Still further, in the above-described embodiment, the locking members 70are configured to be rotated by engaging with the braking member 50.However, the structure which rotates the locking members 70 is notlimited to this. For example, a structure may be employed in whichmoving members, which rotate the locking members 70 between theirlocking positions and unlocking positions, are provided separately fromthe braking member 50. However, in this case, it is preferable that themoving members be configured to operate interiockingly with the brakingmember 50. In any case, with a structure in which the locking members 70are rotated by using the existing braking member 50, there is no need toprovide separate moving members, and therefore, there is the effect thatthe manufacturing cost can be reduced.

The present invention provides a recording tape cartridge in whichsliding resistance at the time when locking members are moved betweenlocking positions and unlocking positions can be lessened, and in whichdeformation of a flange welded to a hub also can be suppressed

A first aspect of the present invention provides a recording tapecartridge comprising: a reel having a hub on which a recording tape iswound, and flanges holding the recording tape wound on the hub, at leastone of the flanges being welded to the hub; a case accommodating thereel singly and rotatably; and a locking member configured to be able torotate within a plane which is orthogonal to a rotation axis directionof the reel around a position which is different from a rotationalcenter of the reel, the locking member being set at a locking position,at which the locking member is interposed on an extended line of the hubin the rotation axis direction at a side where the flange is welded andthe locking member impedes movement of the reel in the rotation axisdirection, and an unlocking position, at which the locking member iswithdrawn from the extended line of the hub in the rotation axisdirection at the side where the flange is welded and the locking memberpermits movement of the reel in the rotation axis direction.

In accordance with the above-described aspect, the locking member is setat the locking position and the unlocking position by rotating within aplane orthogonal to the rotation axis direction of the reel. Accordinglyas compared with a locking member which moves in the radial direction ofthe reel, the moving distance thereof can be shortened, and, as aresult, the sliding resistance can be lessened. Further, because thelocking member presses a position on the extended line of the hub in therotation axis direction at the side where the flange is welded, force isapplied to that flange in a direction of separating from the recordingtape. Accordingly, deformation of the flange (deformation in thedirection of approaching the recording tape) due to tight-windingdeformation of the hub can be suppressed.

In the above-described aspect, the locking member may be configured tobe interposed, from an inner peripheral surface side of the hub, on theextended line of the hub in the rotation axis direction, and does not gobeyond an outer peripheral surface of the hub in plan view.

In accordance with the above-described aspect, the locking member cansuitably press a position on the extended line of the hub in therotation axis direction at the side where the flange is welded. Namely,force is suitably applied to that flange in a direction of separatingfrom the recording tape. Accordingly, deformation of the flange(deformation in the direction of approaching the recording tape) due totight-winding deformation of the hub can be reliably suppressed

In the above-described aspect, the flange which is welded to the hub mayhave an extended portion which engages with an inner peripheral surfaceof the hub

In accordance with the above-described aspect, the extended portion,which engages with the inner peripheral surface of the hub, is providedat the flange which the locking member presses. Therefore, when thelocking member rotates to the unlocking position, the time over whichthe locking member presses this flange can be made to be longer by anamount corresponding to the region (the thickness) of the extendedportion. Accordingly, in a case in which for example, the recording tapecartridge is loaded in a drive device which is disposed vertically,offset of the reel vertically downward can be suppressed by the lockingmember, and poor chucking by the rotating shaft of the drive device canbe avoided.

In the above-described aspect, an engaging surface, which has asubstantially similar curvature as a peripheral surface of the hub, maybe formed at a distal end portion of the locking member which isinterposed on the extended line of the hub in the rotation axisdirection, and a distance to be moved by the locking member between thelocking position and the unlocking position is shortened.

In accordance with the above-described aspect, the surface area of thedistal end portion of the locking member pressing a position on theextended line of the hub in the rotation axis direction can be ensuredto be the maximum. Accordingly, the locking member can suitably press aposition on the extended line of the hub in the rotation axis direction.Further, a distance to be moved by the locking member between thelocking position and the unlocking position can be shortened clue toforming the engaging surface at the distal end portion of the lockingmember.

The above-described aspect may be structured such that the lockingmember is rotated by a moving member which moves in the rotation axisdirection of the reel, the moving member is urged directly or indirectlytoward a floor wall of the reel by a second urging member, and themoving member and the second urging member are provided at an innerperipheral side of the locking member in a radial direction of the reel.

In accordance with the above-described aspect, the structures at theperiphery of the locking members can be simplified.

In this way, the present invention can provide a recording tapecartridge in which sliding resistance at the time when locking membersare moved between locking positions and unlocking positions can belessened, and in which deformation of a flange welded to a hub also canbe suppressed.

The foregoing description of the exemplary embodiments of the presentinvention has been provided for the purposes of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise forms disclosed. Obviously, many modificationsand variations will be apparent to practitioners skilled in the art. Theexemplary embodiments were chosen and described in order to best explainthe principles of the invention and its practical applications, therebyenabling others skilled in the art to understand the invention forvarious embodiments and with the various modifications as are suited tothe particular use contemplated. It is intended that the scope of theinvention be defined by the following claims and their equivalents.

1. A recording tape cartridge comprising: a reel having a hub on which arecording tape is wound, and flanges holding the recording tape wound onthe hub, at least one of the flanges being welded to the hub; a caseaccommodating the reel singly and rotatably; and a locking memberconfigured to be able to rotate within a plane which is orthogonal to arotation axis direction of the reel around a position which is differentfrom a rotational center of the reel, the locking member being set at alocking position, at which the locking member is interposed on anextended line of the hub in the rotation axis direction at a side wherethe flange is welded and the locking member impedes movement of the reelin the rotation axis direction, and an unlocking position, at which thelocking member is withdrawn from the extended line of the hub in therotation axis direction at the side where the flange is welded and thelocking member permits movement of the reel in the rotation axisdirection.
 2. The recording tape cartridge of claim 1, wherein thelocking member is configured to be interposed, from an inner peripheralsurface side of the hub, on the extended line of the hub in the rotationaxis direction, and does not go beyond an outer peripheral surface ofthe hub in plan view.
 3. The recording tape cartridge of claim 1,wherein the flange which is welded to the hub has an extended portionwhich engages with an inner peripheral surface of the hub.
 4. Therecording tape cartridge of claim 1, wherein an engaging surface, whichhas a substantially similar curvature as a peripheral surface of thehub, is formed at a distal end portion of the locking member which isinterposed on the extended line of the hub in the rotation axisdirection, and a distance to be moved by the locking member between thelocking position and the unlocking position is shortened.
 5. Therecording tape cartridge of claim 1, wherein the locking member isrotated by a moving member which moves in the rotation axis direction ofthe reel, the moving member is urged directly or indirectly toward afloor wall of the reel by a second urging member, and the moving memberand the second urging member are provided at an inner peripheral side ofthe locking member in a radial direction of the reel.